The “Content-Type” of a video is an important and in most cases required MIME type for streaming video. Amazon S3 simply echos back whatever MIME type you send when you upload the file. You can set the content-type parameter of a video before sending it to Amazon by appending &content_type= to your S3 destination, for example: http://dbucketname.destination.s3.amazonaws.com/no_ext_file_with_cont_type?acl=public-read&content_type=video/mp4 Note: For .3gp files: Use content_type=video/3gpp For .flv files: Use content_type=video/x-flv We are still looking into a way to set this as a batch server side, such as you would configuring an FTP directory. For now, the Amazon S3 web user interface does allow you to individually modify the properties of each file. Select the file, view Properties, then click the Metadata tab at the bottom. Type in the new value, then click the Save button to apply the new MIME type to the file.
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